- May 31, 2023
-
-
Bart Van Assche authored
Use min() instead of open-coding it in scsi_normalize_sense(). Reviewed-by:
Christoph Hellwig <hch@lst.de> Reviewed-by:
Benjamin Block <bblock@linux.ibm.com> Cc: Douglas Gilbert <dgilbert@interlog.com> Signed-off-by:
Bart Van Assche <bvanassche@acm.org> Link: https://lore.kernel.org/r/20230518193159.1166304-2-bvanassche@acm.org Signed-off-by:
Martin K. Petersen <martin.petersen@oracle.com>
-
- May 23, 2023
-
-
Randy Dunlap authored
Make the chapter heading concise yet still descriptive. This makes the subsystem table of contents more readable (IMO). Signed-off-by:
Randy Dunlap <rdunlap@infradead.org> Link: https://lore.kernel.org/r/20230518212749.18266-12-rdunlap@infradead.org Cc: "James E.J. Bottomley" <jejb@linux.ibm.com> Cc: "Martin K. Petersen" <martin.petersen@oracle.com> Cc: linux-scsi@vger.kernel.org Cc: Jonathan Corbet <corbet@lwn.net> Cc: linux-doc@vger.kernel.org Cc: Matthew Wilcox <willy@infradead.org> Signed-off-by:
-
Randy Dunlap authored
Make the chapter heading concise yet still descriptive. This makes the subsystem table of contents more readable (IMO). Signed-off-by:
-
Randy Dunlap authored
Include "Megaraid" in the chapter heading so that it is clear what subject the document is about. This improves viewing in the TOC. Signed-off-by:
-
Randy Dunlap authored
Make the chapter heading be concise yet still descriptive. This makes the subsystem table of contents more readable (IMO). Signed-off-by:
Finn Thain <fthain@linux-m68k.org> Signed-off-by:
-
Randy Dunlap authored
Make the heading be concise yet still descriptive. This makes the subsystem table of contents more readable (IMO). Spell "CDROM" as "CD-ROM". Capitalize "Linux". Use https instead of http for URLs. Drop the Linux Documentation Project URL for the SCSI generic HOWTO since it hasn't been updated since 2002. Use Doug Gilbert's URL for it instead. Drop some outdated documentation & references. Signed-off-by:
-
Randy Dunlap authored
Fix the typo "Tansport" to be "Transport". Update email address for James Smart. Signed-off-by:
-
Randy Dunlap authored
Make the heading be concise yet still descriptive. This makes the subsystem table of contents more readable (IMO). Signed-off-by:
-
Randy Dunlap authored
Make the heading be concise yet still descriptive. This makes the subsystem table of contents more readable (IMO). Signed-off-by:
-
Randy Dunlap authored
Add a chapter heading so that the document sections are not all at the same level, mucking up the SCSI subsystem contents. Signed-off-by:
-
Randy Dunlap authored
Modify URLs to use https instead of http. Remove ancient URLs that don't work. Change "scsi" in text to "SCSI". Change "cdrom" in text to "CD-ROM". Drop the reference to "autoclean" for modules since I can't find it in any current documentation. Signed-off-by:
-
Randy Dunlap authored
Break the SCSI documentation up into categories: Introduction, APIs, driver parameters, and host adapter drivers instead of alphabetical by document file name (i.e., no organization). Signed-off-by:
-
Gustavo A. R. Silva authored
One-element arrays are deprecated, and we are replacing them with flexible array members instead. So, replace one-element arrays with flexible-array members in a couple of structures, and refactor the rest of the code, accordingly. This helps with the ongoing efforts to tighten the FORTIFY_SOURCE routines on memcpy() and help us make progress towards globally enabling -fstrict-flex-arrays=3 [1]. This results in no differences in binary output. Link: https://github.com/KSPP/linux/issues/79 Link: https://github.com/KSPP/linux/issues/295 Link: https://gcc.gnu.org/pipermail/gcc-patches/2022-October/602902.html [1] Signed-off-by:
Gustavo A. R. Silva <gustavoars@kernel.org> Link: https://lore.kernel.org/r/6c6dcab88524c14c47fd06b9332bd96162656db5.1684358315.git.gustavoars@kernel.org Reviewed-by:
Kees Cook <keescook@chromium.org> Signed-off-by:
-
Christophe JAILLET authored
Bitmaps are "unsigned long[]", so better use "unsigned long *" instead of a plain "void *" when dealing with pointers to bitmaps. This is more informative. Signed-off-by:
Christophe JAILLET <christophe.jaillet@wanadoo.fr> Link: https://lore.kernel.org/r/8bdf9148ce1a5d01aac11c46c8617b477813457e.1683473011.git.christophe.jaillet@wanadoo.fr Signed-off-by:
-
Yuchen Yang authored
Smatch complains that: tw_probe() warn: missing error code 'retval' This patch adds error checking to tw_probe() to handle initialization failure. If tw_reset_sequence() function returns a non-zero value, the function will return -EINVAL to indicate initialization failure. Fixes: 1da177e4 ("Linux-2.6.12-rc2") Signed-off-by:
Yuchen Yang <u202114568@hust.edu.cn> Link: https://lore.kernel.org/r/20230505141259.7730-1-u202114568@hust.edu.cn Reviewed-by:
Dan Carpenter <dan.carpenter@linaro.org> Signed-off-by:
-
Keoseong Park authored
The 'err' variable is used only as the result of ufshcd_hba_init_crypto_capabilities(), so return 'err' immediately when failed. If it is not an error, explicitly return 0. Signed-off-by:
Keoseong Park <keosung.park@samsung.com> Link: https://lore.kernel.org/r/20230503104630epcms2p8b82734102ffb920531e9264604086372@epcms2p8 Signed-off-by:
-
Martin K. Petersen authored
Niklas Cassel <nks@flawful.org> says: This series adds support for Command Duration Limits. The series is based on linux tag: v6.4-rc1 The series can also be found in git: https://github.com/floatious/linux/commits/cdl-v7 ================= CDL in ATA / SCSI ================= Command Duration Limits is defined in: T13 ATA Command Set - 5 (ACS-5) and T10 SCSI Primary Commands - 6 (SPC-6) respectively (a simpler version of CDL is defined in T10 SPC-5). CDL defines Duration Limits Descriptors (DLD). 7 DLDs for read commands and 7 DLDs for write commands. Simply put, a DLD contains a limit and a policy. A command can specify that a certain limit should be applied by setting the DLD index field (3 bits, so 0-7) in the command itself. The DLD index points to one of the 7 DLDs. DLD index 0 means no descriptor, so no limit. DLD index 1-7 means DLD 1-7. A DLD can have a few different policies, but the two major ones are: -Policy 0xF (abort), command will be completed with command aborted error (ATA) or status CHECK CONDITION (SCSI), with sense data indicating that the command timed out. -Policy 0xD (complete-unavailable), command will be completed without error (ATA) or status GOOD (SCSI), with sense data indicating that the command timed out. Note that the command will not have transferred any data to/from the device when the command timed out, even though the command returned success. Regardless of the CDL policy, in case of a CDL timeout, the I/O will result in a -ETIME error to user-space. The DLDs are defined in the CDL log page(s) and are readable and writable. Reading and writing the CDL DLDs are outside the scope of the kernel. If a user wants to read or write the descriptors, they can do so using a user-space application that sends passthrough commands, such as cdl-tools: https://github.com/westerndigitalcorporation/cdl-tools ================================ The introduction of ioprio hints ================================ What the kernel does provide, is a method to let I/O use one of the CDL DLDs defined in the device. Note that the kernel will simply forward the DLD index to the device, so the kernel currently does not know, nor does it need to know, how the DLDs are defined inside the device. The way that the CDL DLD index is supplied to the kernel is by introducing a new 10 bit "ioprio hint" field within the existing 16 bit ioprio definition. Currently, only 6 out of the 16 ioprio bits are in use, the remaining 10 bits are unused, and are currently explicitly disallowed to be set by the kernel. For now, we only add ioprio hints representing CDL DLD index 1-7. Additional ioprio hints for other QoS features could be defined in the future. A theoretical future work could be to make an I/O scheduler aware of these hints. E.g. for CDL, an I/O scheduler could make use of the duration limit in each descriptor, and take that information into account while scheduling commands. Right now, the ioprio hints will be ignored by the I/O schedulers. ============================== How to use CDL from user-space ============================== Since CDL is mutually exclusive with NCQ priority (see ncq_prio_enable and sas_ncq_prio_enable in Documentation/ABI/testing/sysfs-block-device), CDL has to be explicitly enabled using: echo 1 > /sys/block/$bdev/device/cdl_enable Since the ioprio hints are supplied through the existing I/O priority API, it should be simple for an application to make use of the ioprio hints. It simply has to reuse one of the new macros defined in include/uapi/linux/ioprio.h: IOPRIO_PRIO_HINT() or IOPRIO_PRIO_VALUE_HINT(), and supply one of the new hints defined in include/uapi/linux/ioprio.h: IOPRIO_HINT_DEV_DURATION_LIMIT_[1-7], which indicates that the I/O should use the corresponding CDL DLD index 1-7. By reusing the I/O priority API, the user can both define a DLD to use per AIO (io_uring sqe->ioprio or libaio iocb->aio_reqprio) or per-thread (ioprio_set()). ======= Testing ======= With the following fio patches: https://github.com/floatious/fio/commits/cdl fio adds support for ioprio hints, such that CDL can be tested using e.g.: fio --ioengine=io_uring --cmdprio_percentage=10 --cmdprio_hint=DLD_index A simple way to test is to use a DLD with a very short duration limit, and send large reads. Regardless of the CDL policy, in case of a CDL timeout, the I/O will result in a -ETIME error to user-space. We also provide a CDL test suite located in the cdl-tools repo, see: https://github.com/westerndigitalcorporation/cdl-tools#testing-a-system-command-duration-limits-support We have tested this patch series using: -real hardware -the following QEMU implementation: https://github.com/floatious/qemu/tree/cdl (NOTE: the QEMU implementation requires you to define the CDL policy at compile time, so you currently need to recompile QEMU when switching between policies.) =================== Further information =================== For further information about CDL, see Damien's slides: Presented at SDC 2021: https://www.snia.org/sites/default/files/SDC/2021/pdfs/SNIA-SDC21-LeMoal-Be-On-Time-command-duration-limits-Feature-Support-in%20Linux.pdf Presented at Lund Linux Con 2022: https://drive.google.com/file/d/1I6ChFc0h4JY9qZdO1bY5oCAdYCSZVqWw/view?usp=sharing ================ Changes since V6 ================ -Rebased series on v6.4-rc1. -Picked up Reviewed-by tags from Hannes (Thank you Hannes!) -Picked up Reviewed-by tag from Christoph (Thank you Christoph!) -Changed KernelVersion from 6.4 to 6.5 for new sysfs attributes. For older change logs, see previous patch series versions: https://lore.kernel.org/linux-scsi/20230406113252.41211-1-nks@flawful.org/ https://lore.kernel.org/linux-scsi/20230404182428.715140-1-nks@flawful.org/ https://lore.kernel.org/linux-scsi/20230309215516.3800571-1-niklas.cassel@wdc.com/ https://lore.kernel.org/linux-scsi/20230124190308.127318-1-niklas.cassel@wdc.com/ https://lore.kernel.org/linux-scsi/20230112140412.667308-1-niklas.cassel@wdc.com/ https://lore.kernel.org/linux-scsi/20221208105947.2399894-1-niklas.cassel@wdc.com/ Link: https://lore.kernel.org/r/20230511011356.227789-1-nks@flawful.org Signed-off-by:
-
Niklas Cassel authored
A CDL timeout for policy 0xF is defined as a NCQ error, just with a CDL specific sk/asc/ascq in the sense data. Therefore, the existing code in libata does not need to be modified to handle a policy 0xF CDL timeout. For Command Duration Limits policy 0xD: The device shall complete the command without error with the additional sense code set to DATA CURRENTLY UNAVAILABLE. Since a CDL timeout for policy 0xD is not an error, we cannot use the NCQ Command Error log (10h). Instead, we need to read the Sense Data for Successful NCQ Commands log (0Fh). In the success case, just like in the error case, we cannot simply read a log page from the interrupt handler itself, since reading a log page involves sending a READ LOG DMA EXT or READ LOG EXT command. Therefore, we add a new EH action ATA_EH_GET_SUCCESS_SENSE. When a command completes without error, and when the ATA_SENSE bit is set, this new action is set as pending, and EH is scheduled. This way, similar to the NCQ error case, the log page will be read from EH context. An alternative would have been to add a new kthread or workqueue to handle this. However, extending EH can be done with minimal changes and avoids the need to synchronize a new kthread/workqueue with EH. Co-developed-by:
Damien Le Moal <dlemoal@kernel.org> Signed-off-by:
Hannes Reinecke <hare@suse.de> Reviewed-by:
Niklas Cassel <niklas.cassel@wdc.com> Link: https://lore.kernel.org/r/20230511011356.227789-20-nks@flawful.org Signed-off-by:
-
Damien Le Moal authored
For devices supporting the command duration limits feature, translate the dld field of read and write operation to set the command duration limit index field of the command task file when the duration limit feature is enabled. The function ata_set_tf_cdl() is introduced to do this. For unqueued (non NCQ) read and write operations, this function sets the command duration limit index set as the lower 3 bits of the feature field. For queued NCQ read/write commands, the index is set as the lower 3 bits of the auxiliary field. The flag ATA_QCFLAG_HAS_CDL is introduced to indicate that a command taskfile has a non zero cdl field. Signed-off-by:
Igor Pylypiv <ipylypiv@google.com> Reviewed-by:
-
Damien Le Moal authored
Add support for the ATA feature control sub-page of the control mode page to enable/disable the command duration limits feature using the cdl_ctrl field of the ATA feature control sub-page. Both mode sense and mode select translation are supported. For mode sense, the ata device flag ATA_DFLAG_CDL_ENABLED is used to cache the status of the command duration limits feature. Enabling this feature is done using a SET FEATURES command with a cdl action set to 1 when the page cdl_ctrl field value is 0x2 (T2A and T2B pages supported). If this field is 0, CDL is disabled using the SET FEATURES command with a cdl action set to 0. Since a device CDL and NCQ priority features should not be used simultaneously, ata_mselect_control_ata_feature() returns an error when attempting to enable CDL with the device priority feature enabled. Conversely, the function ata_ncq_prio_enable_store() used to enable the use of the device NCQ priority feature through sysfs is modified to return an error if the device CDL feature is enabled. Signed-off-by:
-
Damien Le Moal authored
Modify ata_scsiop_mode_sense() and ata_msense_control() to support mode sense access to the T2A and T2B sub-pages of the control mode page. ata_msense_control() is modified to support sub-pages. The T2A sub-page is generated using the read descriptors of the command duration limits log page 18h. The T2B sub-page is generated using the write descriptors of the same log page. With the addition of these sub-pages, getting all sub-pages of the control mode page is also supported by increasing the value of ATA_SCSI_RBUF_SIZE from 576B up to 2048B to ensure that all sub-pages fit in the fill buffer. Signed-off-by:
-
Damien Le Moal authored
For a scsi MAINTENANCE_IN/MI_REPORT_SUPPORTED_OPERATION_CODES operation, add the translation of the rwcdlp and cdlp bits for the READ 16 and WRITE 16 commands. If the ATA device does not support command duration limits, these bits are always 0. If the ATA device supports command duration limits, the rwcdlp bit is set to 1 for READ 16 and WRITE 16 and the cdlp bits are set to 0x1 for READ 16 and 0x2 for WRITE 16. These correspond to the T2A mode page containing the read descriptors and to the T2B mode page containing the write descriptors, as defined in SAT-5. Signed-off-by:
-
Damien Le Moal authored
Use the supported capabilities identify device data log page to detect if a device supports the command duration limits feature. For devices supporting this feature, set the device flag ATA_DFLAG_CDL. To support SCSI-ATA translation, retrieve the command duration limits log page 18h and cache this page content using the cdl array added to the ata_device data structure. Signed-off-by:
-
Niklas Cassel authored
Currently, ata_eh_request_sense() unconditionally sets the scsicmd->result to SAM_STAT_CHECK_CONDITION. For Command Duration Limits policy 0xD: The device shall complete the command without error (SAM_STAT_GOOD) with the additional sense code set to DATA CURRENTLY UNAVAILABLE. It is perfectly fine to have sense data for a command that returned completion without error. In order to support for CDL policy 0xD, we have to remove this assumption that having sense data means that the command failed (SAM_STAT_CHECK_CONDITION). Change ata_eh_request_sense() to not set SAM_STAT_CHECK_CONDITION, and instead move the setting of SAM_STAT_CHECK_CONDITION to the single caller that wants SAM_STAT_CHECK_CONDITION set, that way ata_eh_request_sense() can be reused in a follow-up patch that adds support for CDL policy 0xD. The only caller of ata_eh_request_sense() is protected by: if (!(qc->flags & ATA_QCFLAG_SENSE_VALID)), so we can remove this duplicated check from ata_eh_request_sense() itself. Additionally, ata_eh_request_sense() is only called from ata_eh_analyze_tf(), which is only called when iteratating the QCs using ata_qc_for_each_raw(), which does not include the internal tag, so cmd can never be NULL (all non-internal commands have qc->scsicmd set), so remove the !cmd check as well. Reviewed-by:
-
Niklas Cassel authored
There is no need to check if !cmd as this can only happen for ATA internal commands which uses the ATA internal tag (32). Most users of ata_scsi_set_sense() are from _xlat functions that translate a scsicmd to an ATA command. These obviously have a qc->scsicmd. ata_scsi_qc_complete() can also call ata_scsi_set_sense() via ata_gen_passthru_sense() / ata_gen_ata_sense(), called via ata_scsi_qc_complete(). This callback is only called for translated commands, so it also has a qc->scsicmd. ata_eh_analyze_ncq_error(): the NCQ error log can only contain a 0-31 value, so it will never be able to get the ATA internal tag (32). ata_eh_request_sense(): only called by ata_eh_analyze_tf(), which is only called when iteratating the QCs using ata_qc_for_each_raw(), which does not include the internal tag. Since there is no existing call site where cmd can be NULL, remove the !cmd check from ata_scsi_set_sense() and ata_scsi_set_sense_information(). Suggested-by:
-
Niklas Cassel authored
Commands using a duration limit descriptor that has limit policies set to a value other than 0x0 may be failed by the device if one of the limits are exceeded. For such commands, since the failure is the result of the user duration limit configuration and workload, the commands should not be retried and terminated immediately. Furthermore, to allow the user to differentiate these "soft" failures from hard errors due to hardware problem, a different error code than EIO should be returned. There are 2 cases to consider: (1) The failure is due to a limit policy failing the command with a check condition sense key, that is, any limit policy other than 0xD. For this case, scsi_check_sense() is modified to detect failures with the ABORTED COMMAND sense key and the COMMAND TIMEOUT BEFORE PROCESSING or COMMAND TIMEOUT DURING PROCESSING or COMMAND TIMEOUT DURING PROCESSING DUE TO ERROR RECOVERY additional sense code. For these failures, a SUCCESS disposition is returned so that scsi_finish_command() is called to terminate the command. (2) The failure is due to a limit policy set to 0xD, which result in the command being terminated with a GOOD status, COMPLETED sense key, and DATA CURRENTLY UNAVAILABLE additional sense code. To handle this case, the scsi_check_sense() is modified to return a SUCCESS disposition so that scsi_finish_command() is called to terminate the command. In addition, scsi_decide_disposition() has to be modified to see if a command being terminated with GOOD status has sense data. This is as defined in SCSI Primary Commands - 6 (SPC-6), so all according to spec, even if GOOD status commands were not checked before. If scsi_check_sense() detects sense data representing a duration limit, scsi_check_sense() will set the newly introduced SCSI ML byte SCSIML_STAT_DL_TIMEOUT. This SCSI ML byte is checked in scsi_noretry_cmd(), so that a command that failed because of a CDL timeout cannot be retried. The SCSI ML byte is also checked in scsi_result_to_blk_status() to complete the command request with the BLK_STS_DURATION_LIMIT status, which result in the user seeing ETIME errors for the failed commands. Co-developed-by:
-
Damien Le Moal authored
Introduce the command duration limits helper function sd_cdl_dld() to set the DLD bits of READ/WRITE 16 and READ/WRITE 32 commands to indicate to the device the command duration limit descriptor to apply to the commands. When command duration limits are enabled, sd_cdl_dld() obtains the index of the descriptor to apply to the command using the hints field of the request IO priority value (hints IOPRIO_HINT_DEV_DURATION_LIMIT_1 to IOPRIO_HINT_DEV_DURATION_LIMIT_7). If command duration limits is disabled (which is the default), the limit index "0" is always used to indicate "no limit" for a command. Signed-off-by:
-
Damien Le Moal authored
Add the sysfs scsi_device attribute cdl_enable to allow a user to enable or disable a device command duration limits feature. CDL is disabled by default. This feature must be explicitly enabled by a user by setting the cdl_enable attribute to 1. The new function scsi_cdl_enable() does not do anything beside setting the cdl_enable field of struct scsi_device in the case of a (real) SCSI device (e.g. a SAS HDD). For ATA devices, the command duration limits feature needs to be enabled/disabled using the ATA feature sub-page of the control mode page. To do so, the scsi_cdl_enable() function checks if this mode page is supported using scsi_mode_sense(). If it is, scsi_mode_select() is used to enable and disable CDL. Signed-off-by:
-
Damien Le Moal authored
Introduce the function scsi_cdl_check() to detect if a device supports command duration limits (CDL). Support for the READ 16, WRITE 16, READ 32 and WRITE 32 commands are checked using the function scsi_report_opcode() to probe the rwcdlp and cdlp bits as they indicate the mode page defining the command duration limits descriptors that apply to the command being tested. If any of these commands support CDL, the field cdl_supported of struct scsi_device is set to 1 to indicate that the device supports CDL. Support for CDL for a device is advertizes through sysfs using the new cdl_supported device attribute. This attribute value is 1 for a device supporting CDL and 0 otherwise. Signed-off-by:
-
Damien Le Moal authored
The REPORT_SUPPORTED_OPERATION_CODES command allows checking for support of commands that have the same opcode but different service actions, such as READ 32 and WRITE 32. However, the current implementation of scsi_report_opcode() only allows checking an operation code without a service action differentiation. Add the "sa" argument to scsi_report_opcode() to allow passing a service action. If a non-zero service action is specified, the reporting options field value is set to 3 to have the service action field taken into account by the device. If no service action field is specified (zero), the reporting options field is set to 1 as before. Signed-off-by:
-
Damien Le Moal authored
Allow scsi_mode_sense() to retrieve sub-pages of mode pages by adding the subpage argument. Change all the current caller sites to specify the subpage 0. Signed-off-by:
-
Niklas Cassel authored
SCSI has two different getters: - get_XXX_byte() (in scsi_cmnd.h) which takes a struct scsi_cmnd *, and - XXX_byte() (in scsi.h) which takes a scmd->result. The proper name for get_scsi_ml_byte() should thus be without the get_ prefix, as it takes a scmd->result. Rename the function to rectify this. (This change was suggested by Mike Christie.) Additionally, move get_scsi_ml_byte() to scsi_priv.h since both scsi_lib.c and scsi_error.c will need to use this helper in a follow-up patch. Cc: Mike Christie <michael.christie@oracle.com> Reviewed-by:
-
Niklas Cassel authored
In SCSI, we get the sense data as part of the completion, for ATA however, we need to fetch the sense data as an extra step. For an aborted ATA command the sense data is fetched via libata's ->eh_strategy_handler(). For Command Duration Limits policy 0xD: The device shall complete the command without error with the additional sense code set to DATA CURRENTLY UNAVAILABLE. In order to handle this policy in libata, we intend to send a successful command via SCSI EH, and let libata's ->eh_strategy_handler() fetch the sense data for the good command. This is similar to how we handle an aborted ATA command, just that we need to read the Successful NCQ Commands log instead of the NCQ Command Error log. When we get a SATA completion with successful commands, ATA_SENSE will be set, indicating that some commands in the completion have sense data. The sense_valid bitmask in the Sense Data for Successful NCQ Commands log will inform exactly whic...
-
Damien Le Moal authored
Introduce the new block I/O status BLK_STS_DURATION_LIMIT for LLDDs to report command that failed due to a command duration limit being exceeded. This new status is mapped to the ETIME error code to allow users to differentiate "soft" duration limit failures from other more serious hardware related errors. If we compare BLK_STS_DURATION_LIMIT with BLK_STS_TIMEOUT: -BLK_STS_DURATION_LIMIT means that the drive gave a reply indicating that the command duration limit was exceeded before the command could be completed. This I/O status is mapped to ETIME for user space. -BLK_STS_TIMEOUT means that the drive never gave a reply at all. This I/O status is mapped to ETIMEDOUT for user space. Signed-off-by:
-
Damien Le Moal authored
I/O priorities currently only use 6-bits of the 16-bits ioprio value: the 3-upper bits are used to define up to 8 priority classes (4 of which are valid) and the 3 lower bits of the value are used to define a priority level for the real-time and best-effort class. The remaining 10-bits between the I/O priority class and level are unused, and in fact, cannot be used by the user as doing so would either result in the value being completely ignored, or in an error returned by ioprio_check_cap(). Use these 10-bits of an ioprio value to allow a user to specify I/O hints. An I/O hint is defined as a 10-bitsvalue, allowing up to 1023 different hints to be specified, with the value 0 being reserved as the "no hint" case. An I/O hint can apply to any I/O that specifies a valid priority class other than NONE, regardless of the I/O priority level specified. To do so, the macros IOPRIO_PRIO_HINT() and IOPRIO_PRIO_VALUE_HINT() are introduced in include/uapi/linux/ioprio.h to respectively allow a user to get and set a hint in an ioprio value. To support the ATA and SCSI command duration limits feature, 7 hints are defined: IOPRIO_HINT_DEV_DURATION_LIMIT_1 to IOPRIO_HINT_DEV_DURATION_LIMIT_7, allowing a user to specify which command duration limit descriptor should be applied to the commands serving an I/O. Specifying these hints has for now no effect whatsoever if the target block devices do not support the command duration limits feature. However, in the future, block I/O schedulers can be modified to optimize I/O issuing order based on these hints, even for devices that do not support the command duration limits feature. Given that the 7 duration limits hints defined have no effect on any block layer component, the actual definition of the duration limits implied by these hints remains at the device level. Signed-off-by:
-
Damien Le Moal authored
The I/O priority user interface defines the 16-bits ioprio values as the combination of the upper 3-bits for an I/O priority class and the lower 13-bits as priority data. However, the kernel only uses the lower 3-bits of the priority data to define priority levels for the RT and BE priority classes. The data part of an ioprio value is completely ignored for the IDLE and NONE classes. This is enforced by checks done in ioprio_check_cap(), which is called for all paths that allow defining an I/O priority for I/Os: the per-context ioprio_set() system call, aio interface and io_uring interface. Clarify this fact in the uapi ioprio.h header file and introduce the IOPRIO_PRIO_LEVEL_MASK and IOPRIO_PRIO_LEVEL() macros for users to define and get priority levels in an ioprio value. The coarser macro IOPRIO_PRIO_DATA() is retained for backward compatibility with old applications already using it. There is no functional change introduced with this. In-kernel users of the IOPRIO_PRIO_DATA() macro which are explicitly handling I/O priority data as a priority level are modified to use the new IOPRIO_PRIO_LEVEL() macro without any functional change. Since f2fs is the only user of this macro not explicitly using that value as a priority level, it is left unchanged. Signed-off-by:
-
Martin K. Petersen authored
Mike Christie <michael.christie@oracle.com> says: The patches in this thread allow us to use the block pr_ops with LIO's target_core_iblock module to support cluster applications in VMs. They were built over Linus's tree. They also apply over linux-next and Martin's tree and Jens's trees. Currently, to use windows clustering or linux clustering (pacemaker + cluster labs scsi fence agents) in VMs with LIO and vhost-scsi, you have to use tcmu or pscsi or use a cluster aware FS/framework for the LIO pr file. Setting up a cluster FS/framework is pain and waste when your real backend device is already a distributed device, and pscsi and tcmu are nice for specific use cases, but iblock gives you the best performance and allows you to use stacked devices like dm-multipath. So these patches allow iblock to work like pscsi/tcmu where they can pass a PR command to the backend module. And then iblock will use the pr_ops to pass the PR command to the real devices similar...
-
- May 17, 2023
-
-
Bagas Sanjaya authored
The Linux kernel isn't in 2.6.x anymore, but rather the major version has advanced much (currently 6.x). Reword the attribution. Also, replace 404'ed 2.4 driver link with web.archive.org snapshot [1]. Link: https://web.archive.org/web/20140129181343/http://www.garloff.de/kurt/linux/dc395/ [1] Signed-off-by:
Bagas Sanjaya <bagasdotme@gmail.com> Link: https://lore.kernel.org/r/20230510093933.19985-4-bagasdotme@gmail.com Signed-off-by:
-
Bagas Sanjaya authored
Sync mailing list address in the documentation to follow MAINTAINERS. Signed-off-by:
-
Bagas Sanjaya authored
Emails to DC395x list bounce (550 error) and visiting the site returns 404 page. Drop both twibble.org links. The driver should now be covered by linux-scsi list. Signed-off-by:
-
